In RPN, the parentheses keys
down of the stack. A roll down causes the stack to roll towards the bottom of the stack, during
which the number in Level 2 to moves down to Level 1, the number in Level 3 to moves down
to Level 2, the number in Level 4 to moves down to Level 3, and the number of Level 1 to moves
(
up to Level 4. The
With the numbers entered into the stack shown in the left column in Figure 6, pressing
performs the roll down of the stack shown in the right column.
Previous Value
Previous Value
77
77
Figure 5 Duplicating a Number on the Stack
(D
manipulate the stack. Pressing
key has a small down arrow on it to indicate the roll down feature.
-15
12
41
23
Figure 6 The RPN Stack and the Roll Down Operation
(
performs a roll
23
-15
12
41
Mathematical Calculations
(
17